Protection for the spliced ends of electric cables is a major concern for electrical contractors, especially when the cables are buried in the ground. A variety of protective devices for this purpose are known to the art. Such prior art devices are illustrated and described, for example, in U. S. Pat. Nos. 3,597,528 and 3,937,870.
The prior art devices, for the most part, comprise a generally tubular member or casing having a side wall, a closed end wall, and an open end, and a second member or plug adapted to mate with the tubular casing and close off the open end of the casing. Passages are provided in either the end wall of the casing or in the end of the plug to permit the conductors to extend into the casing. A bonding and insulating compound or adhesive is disposed within the casing to bond the casing and plug together. This compound substantially fills the interior of the casing and anchors and bonds the conductors in the casing, and it also provides further electrical insulation for the spliced conductors.
While the prior art devices described in the preceding paragraph have many desirable features, the problem of providing a good and reliable weather-tight protective housing for the spliced ends of submerged electrical cables has not been satisfactorily solved in the prior art. One major problem resides in the flow of the uncured bonding or potting compound around the conductors and through the end wall passages during the assembly of the plug and casing, while the compound is in liquid form. This flow results in a weakened bond between the conductor and the walls of the casing, and also often results in voids or openings through which moisture may enter the casing and cause short circuits to the electrical circuit formed by the connection between the conductors.
Another problem in the prior art devices resides in the possibility of a separation of the plug from the casing after assembly. This separation may result from internal pressures created by the assembly of the plug and casing and by the evolution of gases during curing of the potting compound. If the plug separates appreciably from the casing, there will be no effective bonding of the casing and plug, and leakage paths to the interior of the device are created through which moisture may enter into the casing.